There is conventionally known a variable valve device for an internal combustion engine as disclosed in Patent Document 1.
This variable valve device includes a valve stop (deactivation) mechanism capable of stopping (deactivating) the opening and closing of intake and exhaust valves in a part of cylinders of the internal combustion engine. In a high-rotation operation state where engine output is required, bodies of lash adjusters, which serve as pivot points of rocker arms, are fixed by switching members to a cylinder head of the internal combustion engine such that the lash adjusters perform a normal lash adjustment function. When the lash adjusters push down the rocker arms via cams, the rocker arms pivot about their respective one ends. Then, the intake and exhaust valves are driven to be opened and closed at respective given valve lifts by the other ends of the rocker arms.
In a normal operation state where fuel efficiency is required, by contrast, the switching members are moved into the bodies of the lash adjusters so as to stop the opening and closing of the intake and exhaust valves in the part of the cylinders by lost motion of the lash adjusters and thereby allow so-called cylinder cut-off operation during which combustion takes place in the remaining cylinders for improvement of fuel efficiency.